Phase transitions and pre-transitional effects in N-(p-n-pentylbenzylidene) -p-n-pentylaniline (5.5) and its oxygen derivatives - A dilatometric study

Abstract

The density of W-(p-n-pentylbenzylidene)-p-n-pentylaniline (5.5) and its two oxygen derivatives, viz. N-(p-n-pentylbenzylidene)-p-n-pentyloxyaniline (5.O5) and N-(p-n-pentyloxybenzylidene)-p-n-pentyloxyaniline (5O.O5), is reported for the isotropic (I), nematic (N), smectic-G (So) and crystalline (K) phases. Dilatometric results reveal the first order nature of the I-N, N-So and N-K transitions. A rare occurrence of the N-K transition is found for the compound 5O.O5 at a considerably higher temperature. From the observed density data pre-transitional effects are estimated for the isotropic to the first mesomorphic phase. The results are discussed in the light of data reported on other Schiff base benzylidene anilines. © 2005 Verlag der Zeitschrift für Naturforschung, Tübingen.